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1 . Modeless Interaction
Techniques for Text Editing
Larry Tesler
for
Interaction Techniques
CMU HCII
!
5 Feb 2014
2 . The User Experience in 1960
Source: http://www.columbia.edu/acis/history/650.html
3 .Doug Engelbart’s 1968 NLS Demo
Source: http://dougengelbart.org/images/pix/img0029.jpg
4 .An NLS Workstation circa 1969
Source: http://dougengelbart.org/images/pix/wke.jpg
5 . [Xerox] PARC — Founded 1970
Source: Wikimedia Commons. Photo by Coolcaesar.
6 .Me and my Alto at PARC in 1975
7 . Early Mice
SRI 1963 1968
Telefunken 1968 1972
Xerox PARC 1973
Image sources: dougengelbart.org, oldmouse.com, Wikimedia Commons
8 .User Studies I ran in 1973
The main subject was our secretary
Blank screen study findings included:
She wanted and expected WYSIWYG
To delete [imaginary] text she would run
her finger across it on the screen and
press a Delete key (verb after object)
Studies of RCG (an NLS subset)
Syntax was verb before object
9 . NLS and RCG delete syntax
verb noun mark OK
Delete Character
Word
Statement
Text (2 marks)
10 . NLS and RCG editing syntax
verb noun mark OK
Delete
Character
Move
Word
Insert
Statement
mark
Replace Text (2 marks)
11 .RCG user study Aug 1973
12 .Conclusions that endured
Character keys type characters, not
commands
The intuitive use of a mouse is to point at
things, not to accept and delete commands
There is a “cursor” displayed showing
where the next character typed will appear
There are two ways to move the cursor:
keystrokes and mouse pointing
13 .Conclusions we abandoned
There are no invisible characters; carriage
return is a command, not a character
Space bar and carriage return should do
what they do on typewriters
Keys that don’t exist on typewriters do
nothing until the user has learned them
The mouse is taught late; its best aspects are
emphasized to make a positive impression
15 .Design done with Jeff Rulifson
16 .Design done with Jeff Rulifson
17 .Objections to cut & paste
1. Unfamiliar metaphor (in the ‘60s and ‘70s)
2. User mistakes (e.g., forgot to paste)
3. Speed compared to NLS
4. Extensibility to other applications
18 .Advantages of cut & paste
1. Fewer errors because there can’t be any
mode errors.
19 .Advantages of cut & paste
1. Fewer errors because there can’t be any
mode errors.
2. Speed. Roberts and Moran (1983) showed
that experienced Gypsy users, on average,
performed tasks in two-thirds the time of
NLS. Fewer key presses were required.
20 . Roberts & Moran Results
Source: “The evaluation of text editors: methodology and empirical results” by Teresa L. Roberts and Thomas P. Moran, CACM 26(4) April 1983 pp. 265-283
21 .Advantages of cut & paste
1. Fewer errors because there can’t be any
mode errors.
2. Speed. Roberts and Moran (1983) showed
that experienced Gypsy users, on average,
performed tasks in two-thirds the time of
NLS. Fewer key presses were required.
3. Modeless. The ability to do other things
between cut and paste entails more
benefits than risks.
22 .What is a mode?
A mode is a state of the user interface that
lasts for a period of time, is not associated
with any particular object, and has no role
other than to place an interpretation on
operator input.
23 .Prefix vs. suffix syntax in editors
Prefix Syntax
<verb> <object>
After the verb, the editor must enter a mode
to wait for the user to specify the object.
Suffix Syntax
<object> <verb>
After the verb, the editor can perform the
command immediately. No mode is needed.
24 .How modes degrade usability
!
Keeping track of mode changes can distract
a user from the task at hand.
If the current mode is misjudged,
unintended and sometimes disastrous
results ensue.
Users often get “stuck” in a mode and ask,
“How do I get out of this mode?”
25 .Image source: Gypsy manual, Xerox PARC
26 . Modeless Search, Move and Copy
Image source: Gypsy manual, Xerox PARC
27 . Modeless Search, Move and Copy
Image source: Gypsy manual, Xerox PARC
28 . Modeless Search, Move and Copy
Image source: Gypsy manual, Xerox PARC
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